Film processor having means for retaining a film loop at constant length in a u-shaped conduit



Nov, 15, 1949 v. E. PRATT ET AL 2,488,141

FILM PROCESSOR HAVING MEANS FOR RETAINING A FILM LOOP AT CONSTANT LENGTHIN A U-SHAPED CONDUIT 4 Sheets-Sheet 1 Filed March 7, 1945 INVENTOR.VERA/EUR E. PRATT GEORGE E GRAY N 1949 n v. E. PRATT ETAL.

FILM'PROCESSOR HAVING MEANS FOR RETAINING A FILM LOOP AT CONSTANT LENGTHIN A U'SHAPED CONDUIT Filed March 7, 1945 1 Sheets-Sheet 2 NQW m W vw Wi w A INVENTOR.

Nov. 15, 1949 v #RATT ETAL 2,488,141

FILM PROCESSOR HAVING MEANS FOR RETAINING A FILM LOOP AT CONSTANT LENGTHIN A U-SHAPED CONDUIT 4 Sheets-Sheet 3 Filed March 7. 1945 INVENTOR.VERNEUR E. PR47'7' GEORGE E GRAY Nov. 15, 1949 v. E. PRATT EI'AL2,488,141

FILM PROCESSOR HAVING MEANS FOR RETAINING A FILM LOOP AT CONSTANT LENGTHIN A U-SHAPED CONDUIT n INVENTOR. VERNEUR 5. PRATT N Q q 3 BY GEORGE EGRAY a ,2 I? E I 'fjmam w &

Patented Nov. 15, 1949 FILM PROCESSOR HAVING MEANS FOR RE- TAINING AFILM LOOP '1" OFFICE AT CONSTANT LENGTH IN A U-SHAPED CONDUIT Verneur E.Pratt and George F. Gray, Norwalk, Conn.

Application March 7, 1945, Serial No. 581,355

Claims. 1

This invention relates to improvements in film processors wherein thefilm to be processed is moved through a series of U-shaped conduits,each of which may contain a fluid employed in processing the film, thefilm being fed into one leg of each U by a cooperative driving anddriven roller, and being removed from the other leg of the U by a secondcooperative driving and driven roller; and is directed more particularlyto maintaining a uniform loop of film within the U- shaped conduit andbetween the two pairs of cooperative rollers which deliver it to andremove it from the conduit.

This invention is a continuation in part of copending application SerialNumber 573,438, filed January 18, 1945, now Patent No. 2,424,052, datedJuly 15, 1947.

In said co-pending application the cooperating driving and drivenrollers are comprised of a driving roller, the diameter of which issubstantially equal to the distance between two planes extending fromthe axes of the two legs of the U -shaped conduit, and the drivenrollers are adjusted with respect to said driving roller a distancegreater than the thickness of the film and less than the l thickness ofa thick leader which is attached to the film for propelling it throughthe array of rollers and U-shaped conduits, thereby pulling the filmthrough without permitting its emulsion surface to become scratched.

According to the present invention, in line with a plane extending fromeach leg of the U-shaped conduits is a cooperative pair constituting adrive and a driven roller. Thus, each U-shaped conduit employs a pair ofdriving and driven rollers in line with each of its straight legs. Thedriving rollers are of exactly the same diameter and are driven by acommon driving means. The cooperative driven rollers are carried onindividual pivoted supports and these supports are joined together byspring means urging them into contact with their cooperative drivingrollers. By employing a unit spring means having one end attached to onepivoted support and its other end attached to its other pivoted support,the force alignment with each leg a pair of cooperative riving anddriven rollers;

Figure 2 is a plan view showing the mechanism for driving the drivingrollers and the relation of the driven rollers thereto;

Figure 3 is an elevation partly in section taken along the line 33 ofFigure 2;

Figure 4 is a sectional elevation as seen along line ll of Figure 1;

Figure 5 is a sectional View of the U-shaped conduit as seen along theline 55 of Figure 4; I

Figure 6 is a perspective view of one of the free roller pivotalsupports; and

Figure 7 is a diagrammatic sketch showing a complete processing systememploying driving means according to the present invention. 7

Referring first to Figure 1, a supporting wall 2% carries a reel shaft2! adapted to support a reel 22 containing exposed film. The film,designated by the numeral 2l5, passes over a free roller 24 and is fedbetween rollers to be presently described.

Behind the wall Zil, as may beseen in Figure 2, is a pair of spacedparallel supporting members 25 and 26. A cradle 21, the details, ofconstruction of which will be described in connection with Figure 6, ispivotally carried between the supports 25 and 2E. Journalled in thecradle 21 is a shaft 28 which has keyed thereto a gear 29 which mesheswith a gear at, which will be presently described. A cross pin 3| in theshaft 28 is engaged by a slot formed in the hub 32 of a roller 33. Theroller 33 is secured to the shaft 28 by meansvof an end screw 35. Ashaft 35 is journalled in suitable bearings in the supports 25 and 26,and has keyed thereto the gear 3B which was described above as meshingwith the gear 29. The shaft 35 also has keyed thereto a worm gear 35.This shaft also carries suitable collars to eliminate any end play. Across pin 3? in the shaft 35 is engaged by a slot formed in the hub 38of a roller 39. The roller 39 is secured to the shaft by an end screw40.

Spaced apart from the shaft 35 is a like shaft 4| which is alsojournalled in suitable bearings in the supports 25 and 25. The shaft 4!has keyed thereto a spur gear i2 identical with the spur gear 30. A wormgear 43 is also keyed to the shaft 4 land is in alignment with the wormgear 36, and common to those two worm gears is a worm shaft M which isdriven by a suitable gear reduction. A cross pin 2-5 in the shaft 41 isengaged by a slot in the hub 26 of a roller 4?, and this roller is heldonto the shaft by means of an end screw 48.

A cradle 59 is pivotally mounted between the supports 25 and 2t and ashaft journalled in the cradle carries a gear 5| which meshes with thegear 42. A cross pin 52 in the shaft 50 is engaged by a slot in the hub53 of a roller 54 secured on the shaft by means of an end screw 55. Thecradle has an upwardly projecting lug 56. Likewise the cradle 49 has anupwardly pro- J'ecting lug 51. Between the shafts 35 and 4| is mounted adistance rod 58 which is secured to the support plate 25 by means of ascrew 59 and secured to the support plate 26 by means of a screw 69. Ahelical spring 6| has one end connected to the lug 56 and its other endconnected to the lug 51. Since the spring 6| freely spans the spacebetween the lugs 56 and 51, its urge upon the cradles is exactly thesame, with the result that the cradle 21 is urged to the right, as seenin Figure 2, and the cradle 49 is urged to the left with equal force,and the tensional engagement of the roller 33 with the drive roller 39is exactly the same as the tensional engagement of the roller 54 withthe drive roller 41. It will be remembered that the shafts 35 and 4| aredriven, respectively, through the worm gears 36 and 43 actuated by theworm shaft 44, so that the direction of rotation of the driving rollers,as may be seen in Figure 1 indicated by the arrows, iscounter-clockwise.

Since the spur gears 29, 38 and 5|, 42 are in definite ratio to thediameters of the rollers 33, 39 and 54, 41, respectively, the regulationeffected by the spring 6| falls within the backlash of the meshed gears.A cradle 62, identical with the cradle 21, is pivotally carried betweenthe supports 25 and 26, and journalled in the cradle 62 is a shaft 63which has keyed thereto a gear 64 which meshes with a gear 65. A crosspin 69 in the shaft 63 is engaged by a slot formed in the hub 61 of aroller 68 which is in turn secured to the shaft by an end screw 69. Ashaft is journalled in suitable bearings in the supports 25 and 26, andhas keyed thereto the gear 65 which meshes with the gear 64. A worm gearH is keyed to the shaft 19 and meshes with the worm 44. The shaft 19also carries suitable collars to eliminate end play, and a cross pin 12therein is engaged by a slot formed in the hub 13 of a roller 14. Ascrew in the end of the shaft 10 retains the roller 14 on the shaft.

Spaced apart from the shaft 19 is a like shaft 16 journalled in suitablebearings in the supports 25 and 26. This shaft has keyed thereto a spurgear 11 identical with the gear 65, and a Worm gear 18 identical withthe Worm gear 1! and also meshing with the worm 44. The shaft 16 alsocarries suitable collars to eliminate end play and is provided with across pin 19 which engages a slot formed in the hub 80 of a roller BIsecured to the shaft by means of an end Screw 82.

A cradle 83 like the cradle 49 is pivotally mounted between the supports25 and 26, and a shaft 84 journalled in the cradle has keyed thereto agear 85 which meshes with the gear 11. The shaft 84 has a cross pin 86mounted therein and engaged by a slot formed in the hub 81 of a roller88 which is retained on the shaft by means of an end screw 89. Thecradle 62 has an upstanding lug 90 formed thereon and. the cradle 83 hasan upstanding lug 9| formed thereon. A helical spring 92 is secured tothe lugs 90 and 9| and freely spans the space therebetween.

Spaced shafts 93 and 94 are journalled in the supports 25, 26, and havekeyed thereto, respectively, spur gears 95, 96 and worm gears 91, 98.These shafts also have cross pins 99, I99, respectively, engaged byslots formed in the hubs IN,

'4 of a roller I02; and I03 of a roller I04, said roller being retainedon said shafts by means of end screws I05, I06. Both of these shafts areprovided with collars to eliminate end play, and both the worm gears 91,98 mesh with the worm 44.

A cradle I01 is pivotally carried in the supports 25 and 26 between theshaft 93 and the cradle 83, and a second cradle I 98 is pivotallymounted in the supports to the right of the shaft 94. The cradle I91carries a shaft I99 to which a gear H0 is keyed. The shaft I99 alsocarries a cross pin I I I which is engaged by a slot formed in the hubII2 of a roller II 3 retained on the shaft by means of an end screw H4.The gear I I0 meshes with the gear 95.

The cradle I08 carries a shaft II5 to which a gear II6, meshing with thegear 96, is keyed. A cross pin H1 in the shaft II5 engages a slot formedin the hub I I8 of a roller I I9 retained on the shaft by means of anend screw I20. The cradle I01 has an upstanding lug I2I formed thereonand the cradle I08 has a like lug I22. A spring I23 has its ends securedto the lugs I2I and I22 and freely spans the space therebetween.

Several distance rods, like the distance rod 58 above described, areemployed for properly spacing the supports 25 and 26.

The worm 44 projects from each side of a gear reduction unit I24, and ashaft I25 extending therefrom at a right angle to the worm 44 carries ashive I26 which may be belted to a pulley on a prime mover forfurnishing power thereto.

The shaft 10 may extend rearwardly from the support 26 and may havekeyed thereto a sprocket I 21 which may be connected to a take-up reelin a dryer for the processed film but, since the dryer forms no part ofthe present invention, it need not be described herein,

Referring now to Figure 6, the cradle, generally designated by thenumeral 21, includes a side portion I28, and spaced apart therefrom, asecond side portion I29 joined together by a lower web I30 and an upperweb I31. The side portion I28 carries a bearing boss I32 and the portionI29 carries a like bearing boss I33 in alignment therewith and in whichthe shaft 28 is journalled. The shaft 26 has keyed thereto the gear 29and also carries a collar or spacer sleeve I39 and a washer I40 toeliminate end play. The portion I28 carries a boss I34 on the lower endthereof, and this boss is tapped to accommodate the threads of ashouldered Screw I 35, means (not shown) being provided for locking thescrew in the boss I34 after assembly. The portion I29, on its lower end,also carries a boss I36 which is tapped to accommodate the threads of ashouldered screw I31. When assembled, the straight shanks of theshouldered screws I35 and I31 are journalled in the supports 25 and 26.The lug 56 extends upwardly from the web I3I and is provided with a holeI38 to be engaged by the end of the spring 6 I.

Since the cradles 49, 62, 83, I01, I98 are identical with the cradle 21,they need not be described in detail.

The supports 25 and 26 are secured to the supporting Wall 20 in anysuitable manner, for example, by means of screws I4I extending throughthe wall 20 and threadedly engaging the supporting member 25 with aspacer washer I42 therebetween.

Returning to Figure 1, a U-shaped conduit I56, the cross section ofwhich may be seen in Figure 5, consists of parallel sides I69 and I6Ijoined by angular portions I92 and IE3 on one side forming an apex I64.Similar sides I65 and IE6 join the sides I60 and NH and meet at an apexI61. The film 2I5 normally clears the conduit I59 and the like points ofcontact with the conduit are on the extreme edges.

One leg of the conduit I59 has flares I68 and I69 formed thereon. Theseflares are oppositely disposed, I68 being adjacent to the roller 33 andI69 being adjacent to the roller 39. The other leg of the conduit issimilarly flared at I10 and HI.

One leg of the conduit has aligned holes I12 and I13 formed therein andin alignment with these holes in the other leg are formed aligned holesI14 and I15. A hollow casing I16 extends laterally from the wall 20 andhas an upstanding flange I11 which is secured to said wall by means ofscrews I18. The hollow casing I16 has clearance passages formed therein:to accommodate the legs of the conduit I59, and these legs and thecasing are soldered or brazed together to form a fluid tight joint.

The purpose of the casing I19 is to receive the processing fluid (whichis forced through the conduit by means of a pump to be presentlydescribed) as the fluid is ejected through the openings I12, I13, I14and I into the exterior of casing I16.

The casing I16 has a hole I85 formed in the bottom wall thereof and thishole is fitted with a bushing I86 to which is attached a short pipe I81,which extends into the open end of a tank I88 secured to the Wall 20.Thus, fluid passing from the openings I12 to I15, inclusive, and intothe casing I16 flows out through the hole I85 and via the pipe I81, andis delivered to the tank I88. At the bottom the U-shaped conduit I59 hasaligned holes I89 and I90 formed therein. A hollow casing I! has aflange I92 which is secured to the wall 29 by means of screws I93. Theconduit is positioned in the hollow casing I9I as shown and is solderedor brazed thereto to form a fluid tight joint.

A nipple I95 has one end in communication with the casing I9I andextends through the wall and is in fluid tight engagement with a fittingI43 formed of rubber or the like. A pipe I44 has one end connected tothe fitting I43 and the other end is connected to the outlet I96 of apump I91. The fitting I43 may be supported on the rear of the wall 29 bymeans of a bracket I45 secured thereto and carrying clamping means I46embracing the fitting I43. The pipe I98 has its lower end incommunication with the interior of the tank I88 and its upper end isconnected to the inlet I99 of the pump I91. The pump is directlyconnected to an electric motor 209. When the motor is turned on, fluidis drawn from the tank I88 via the pipe I98 to the inlet of the pump andthence, via the outlet I96, via the pipe I44, the fitting I43 and thenipple I95, fluid is delivered to the hollow casing I9I. The fluid thenpasses via the aligned holes I89 and I99 into the U-shaped conduit I59where it divides, and part of it passes up the left leg, as seen inFigure 1, then outwardly from the conduit via the holes I12 and I13 intothe hollow casing I16. Part of re fluid also passes up the right leg andout via the holes I14 and I15 into the hollow casing I16. The fluidflows from the casing via the pipe I81 and returns to the tank I88.

The fluid entering the conduits via the holes I89 and I90 hassubstantial velocity, and therefore, it washes ofi any deposits on thesurface of the film due to the processing fluid. This is'particularlyimportant in cases where fixer-developers are used in our apparatus. Theaction of the fixer-developer results in a deposit on the surface of theemulsion, which deposit shields the emulsion from free action by thesolution. However, the velocity of the fluid up both legs of the conduitwashes oil" the coating or deposit, thereby leaving the surface of theemulsion open to the continued action of the fixer-developer.

The hollow casing I9I is provided with a suitable drain cock 29I bymeans of which the entire system may be drained into a container ortrough 292 in the bottom of the'machine.

A second U-shaped conduit I59 is identical with the conduit I59 and hasassociated therewith a hollow casing I19 and a discharge pipe I81discharging into a tank I88.

At the bottom of the U is a hollow casing I9I like the hollow casingI9I. A pump I91 similar to the pump I9! is provided for drawing liquidfrom the tank I88 and delivering it to the hollow casing I9I A thirdU-shaped conduit I59, is identical with the conduit I59 and hasassociated therewith a hollow casing -I1Ii and a discharge pipe I81discharging into a tank I88 At the bottom of the U is a hollow casingI9I like the hollowing casing I9I. A pipe 203 has one end connected tothe hollow casing I9I (see also Figure '7) and the other end of thispipeis connected to a solenoid valve 204 which is in turn connectedthrough a mixing valve 205 for mixing hot and cold water together todeliver water at a predetermined temperature. A pipe 206 leads from themixing valve to a'source of cold water under pressure and a pipe 201 isconnected to the mixing valve 205 and leads to a source of hot waterunder pressure.

The mixing valve 205 is provided with a thermostatic control 298 whichautomatically controls the temperature of the water delivered by thepipe 203.

The valve 204 includes a solenoid 209 which is connected via a pair ofwires 2 I 0 and a switch 2I I to a source of current 2I2.

The switch ZII, when turned on, supplies energy to both the motor 200and the motor 200* and to the solenoid 209 on the valve 204. Thus, whenthe machine is turned on, the pump I91 driven by the motor 200circulates fluid in'the U-shaped conduit I59, the pump I91, driven bythe motor 200*, circulates fluid in the U-shaped conduit I59 and thesolenoid valve 204 is opened and delivers warm water to the U-shapedconduit I59".

It has been described above that the processing fluid circulated throughthe U-shaped conduits I59 and I 59 returns to the pumps and isrecirculated. However, the washing water which is delivered via the pipe203 to the U-shaped conduit I59 overflows into the hollow casing I16",passes down the pipe I81 into the tank I88 and thence passes to thesewer or drain via a pipe 2I3, the upper end of which is connected tothe bottom of the tank I88 From the above description it will be clearlyunderstood that the reel 22' of exposed film 2I5 may be positioned onthe stud 2I, and the end of the film may be passed over the roller 24and inserted between the drive roller 39 and its companion roller 33.Since the roller 33 is urged toward the roller 39 by means of the springBI, the film starts feeding down the left leg of the conduit I59 and asthe'rollers continue o feed the film, it passes around the curved lowerend of the conduit I59 and upwardly in the right leg of the conduit. Asthe film is leaving the upper end of the right leg, it enters betweenrollers 41 and 54 which also tensionally engage the film under the urgeof the spring 6|. Since the spring 6| has a free span, the urge of theroller 3 against the film is exactly equal to the urge of the roller 33against the film. Therefore, the pair of rollers 41, 54 will remove filmfrom the U-shaped conduit I59 at exactly the same rate the film isdelivered thereto by the pair of rollers 33, 39.

An arcuate channel I41 spans the space between the line of contact ofthe rollers 47, 54 and the line of contact between rollers 68, 14. Asthe end of the film 2I5 is moved upwardly by the rollers 31, 54, thearcuate channel I l! guides the end of the film and ensures its deliverybetween the rollers 68, M. The latter rollers feed the film downwardlyinto the conduit I59 and then the film passes around the bottom and upthe right leg to be engaged by the rollers I04, I I9, and from theserollers the film may pass to a dryer which forms no part of the presentinvention.

Referring again to Figure 7, applicants provide a drain pan or trough202 in the bottom of the machine. This drain pan or trough is providedfor catching any fluids which spill or which are dumped from the system.Applicants also provide a dirigible nozzle 2l6 which is connected bymeans of a flexible hose 2|! to the pipe 203. The nozzle may have aplunger valve 2l8 with a handle 2H3 so that the operator may turn thespray nozzle off or on at will for washing down the interior of themachine or flushing out and draining the several tanks and conduits inthe machine.

Another important use of the nozzle 216 is in connection with mixing theprocessing solutions. For example, the powdered, pulverized and/orliquid chemicals may be placed in the bottom of the proper tank I88,then the operator may, by means of the nozzle 2l6, fill the tank untilthe liquid level reaches the line indicated by the numeral 2 l9, andthereby add the proper amount of water for the charge of chemicals. Thecharge of chemicals may be proportioned so that one charge willcompletely process a roll of film, following which the operator may, bymeans of the drain cock 2B1, empty the tank of solution. This ispreferably done with the pumps operating so that when the system isdrained additional water may be added to the tanks, and this will bepumped through the pump and out by the drain cocks and thereby flusheach section of the machine.

The drain pan has a sump 220 formed therein preferably adjacent to oneend thereof. A pump 22! has its inlet connected to one end of a pipe222, the other end of which extends into the sump. The outlet of thepump is connected to a pipe 223 which leads to the sewer. The pump 22lis directly connected to a motor 224, and this motor is connected viaswitch 225 to the source 2l2, so that any time it is desired to removefluid from the drain pan 202, it is only necessary to turn the switch225 and set the pump 22l into operation.

The pulley l 26 on the gear reduction 124 is connected via a belt 225 toa pulley 221 which is secured to the shaft of a driving motor 228. Thedriving motor 228 is connected via a pair of wires 229 to the wires 2H3so that the switch 2 may,

8 in addition to controlling the solenoid 209 and the motors driving thepumps I91, l 91, also eifect the driving of the series of drivingrollers driven by the worm shaft 44.

All of the rollers, both the drive rollers and the free rollers (as wasthe case in the above mentioned application of which the presentapplication is a continuation in part) have rims formed of rubber or thelike. Therefore, the film passing between cooperating drive and freerollers is positively driven, due to the frictional engagement by saidrubber-like rims, and the chance of the film becoming scratched isminimized.

Although but one specific embodiment of this invention has 'been hereinshown and described, it will be understood that numerous details of theconstruction shown may be altered or omitted without departing from thespirit of this invention, as defined by the following claims.

What is claimed is:

1. In a device for processing film, a U-shaped conduit for containingprocessing fluid, said conduit having vertical legs with open ends,means supporting said conduit, a frame, a pair of cradles pivotallysupported on said frame in spaced relation to each other and in definiterelation to said open ends, a shaft journalled in each of said cradlesand a free roller mounted on each of said shafts, a pair of driverollers journalled in said frame between said cradles, both said freeand said drive rollers having rubber-like rims, said drive rollers beingadapted to be engaged by said free rollers on lines of contact above andin line with said open ends, a spring secured to and forming a free spanbetween said cradles, said spring being adapted to exert equal urges ofsaid free rollers against the cooperating drive rollers; a free loop offilm extending between one pair of cooperating rollers, through saidconduit and between the other pair of cooperating rollers; and means fordriving said drive rollers at an identical rate of speed, whereby thelength of said loop remains substantially constant.

2. In a device for processing film, a support, a plurality of U-shapedconduits carried on said support for containing fluids, said conduitshaving open ended vertical legs, a set of rollers for each conduitcomprised of a pair of adjacent rollers of equal diameters driven at thesame rate of speed, said rollers being positioned between a second pairof free rollers which are movable toward the driven rollers and adaptedto urge the film into contact with said drive rollers along lines lyingon planes extending through said legs, pivoted cradles supporting shaftscarrying said free rollers, at least the cooperative faces of all saidrollers being formed of rubber-like material, and a spring secured toand forming a free span between said cradles for causing said freerollers to urge the film as aforesaid, whereby film passing between oneof said rollers and its cooperating free roller is fed into said conduitat exactly the same rate as film passing between the other of said driverollers and its cooperating free roller is removed from said conduit,said film forming a free loop between said rollers and lying within saidconduit.

3. In a device for processing film, a support, a U-shaped conduit onsaid support for containing processing fluid, said conduit havingvertical legs with open ends, an array of rollers above said conduitcomprised of a pair of adjacent rollers of equal diameters, said rollersbeing carried on shafts positioned between a second pair of mov-.

ably supported rollers which contact said first rollers along linessubstantially in line with the open tops of said conduit, at least theperipheral faces of all said rollers being of rubber-like material,means for driving said first rollers at the same speed, spaced pivotedcradles supporting shafts carrying said second rollers, and a singlespring secured to and freely spanning the space between said cradles,whereby a film inserted between one of said first rollers and itscooperating free roller is fed into one leg of said conduit at exactlythe same rate said film, after passing down said leg and up the otherleg, is removed from said conduit by the other of said first rollers andits cooperating free roller, said film forming a free loop between saidrollers and lying within said conduit.

4. In a device for processing film, a support, a plurality of U-shapedconduits carried on said support for containing fluids, an array ofrollers above the open ends of the legs of said conduits and comprisedof a free roller and a drive roller for each leg of each conduit, twodrive and two free rollers forming a set, said drive rollers of each setbeing positioned between said free rollers of each set and each of thelatter being movabl positioned with respect to and adapted to cooperatewith its corresponding drive roller, and spring means common to andurging both the free rollers of each set into contact with the driverollers of the same set, whereby film passing through said array andlooped through each of said conduits in the form of a free loop isdelivered to one leg of each U and removed from the other leg thereof atthe same rate.

5. In film processing apparatus, a frame forming a support, a cradlehaving a shaft journalled therein, means pivotally carrying said cradleon said support, a second cradle having a shaft journalled therein,means pivotally carrying said second cradle on said support in spacedrelation to said first cradle, rollers secured to said shafts and termedfree rollers, a pair of driven shafts journalled on said frame betweensaid cradles in spaced relation to each other, said last shafts 10 beingdriven in unison, other rollers secured to said driven shafts and termeddriven rollers, the peripheral faces of all said rollers being smoothand toothless and formed of rubber-like material, and a spring havingone end secured to one of said cradles and having its other end securedto the other of said cradles for urging said free rollers toward saiddriven rollers, whereby a free loop of film formed between the two pairsof cooperating free and driven rollers is maintained constant by thedelivery of film thereto solely by one of said pairs and by the equalremoval of film therefrom solely by the other of said pairs. VERNEUR E.PRATT. GEORGE F. GRAY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 757,323 Lienekampf Apr. 12, 19041,570,809 Wescott Jan. 26, 1926 1,637,658 Rose Aug. 2, 1927 1,656,522Josepho Jan. 17, 1928 1,809,830 Cobb June 16, 1931 1,831,562 I-IeislerNov. 10, 1931 1,847,663 Newman Mar. 1, 1932 1,890,490 Barkelew Dec. 13,1932 1,991,249 Ingman et al Feb. 12, 1935 2,020,419 Knowlton Nov. 12,1935 2,043,853 Howell June 9, 1936 2,048,182 De Ybarrondo July 21, 19362,085,188 Gerlach Jan. 29, 1937 2,186,927 Hughey Jan. 9, 1940 2,337,864Beidler Dec. 28, 1943 2,373,107 Duffy Apr. 10, 1945 2,401,185 Pratt May28, 1946 FOREIGN PATENTS Number Country Date 529,933 Germany July 23,1931 594,938 Germany Mar. 24, 1934 844,158 France Apr. 11, 1939

